PHILADELPHIA – When the Eagles began training camp, it was widely assumed that the most intriguing battle for a starting job would be at safety between veteran Nate Allen and Earl Wolff.

Instead, that seems to be happening at cornerback, where Nolan Carroll, a free agent signee from Miami, is challenging returning starter Bradley Fletcher.

Eagles defensive coordinator Bill Davis all but conceded the job to Allen, who started all three preseason games and played well in each.

"I think Nate has the lead, but it's not over yet," Davis said.

Davis had a much different take when he was asked if Fletcher will be the starter when the Eagles open the season Sept. 7 against Jacksonville.

"Nothing is in stone yet," Davis said. "I don't want to go ahead with another [preseason] game left and say, 'Who's the starter? Who's not?' A lot of it is pretty much there. I would say it's still all penciled in. Anything can happen. We've got another two weeks of practice and another [preseason] game. So it's getting closer and closer."

Carroll, who played for the Miami Dolphins the previous four seasons, returned to practice last week after missing two weeks with a groin injury. Before the injury, the coaches raved about his play, going back to the spring OTAs.

Carroll, who had an interception in the Eagles' 31-21 win over the Steelers last Thursday, said he's not getting caught up in the competition for a starting job.

"The competition questions, you have to ask coach about that," he said. "It's something I can't really answer. I'm just out there trying to do my job."

Even if Carroll doesn't start, the Eagles seem to have big plans for him. They have been using him in "dime" packages, when there are six defensive backs on the field in obvious passing downs. It's something the Eagles couldn't do last season because of their lack of depth in the secondary.

Carroll said that indicates the defense should be much improved than last season, when it was last in the NFL against the pass, giving up an average of 289.8 passing yards per game.

"Whatever role I can have on the defense, I'm accepting of it," Carroll said. "People kind of look at the defense, and they really just look at the passing yardage, and say, 'They weren't as good.' You have to think of the type of offense [the Eagles] have. They're just scoring points back to back to back like that, and the defense is on the field longer, like 80-something plays [per game].

"It's kind of screwed up how everybody looks at just stats. You have to look at the other side the ball, at what our offense is doing."

As for the safety competition, Eagles coach Chip Kelly said Sunday that Wolff would start the final preseason game and that Allen would sit unless they need him for depth. Kelly was then asked if that means Allen is the starter. He replied: "Earl needs a lot more reps."

Wolff said he agrees. As a rookie last season, Wolff played well until hurting his knee against Green Bay. He missed six games and tried returning against Chicago on Dec. 22. He lasted just one quarter before coming out. He said it has taken him awhile to adjust to game speed this preseason.

"The first game, I felt like I wasn't seeing everything," Wolff said. "I felt like I saw more in that last game ... I feel like I need to be on the field more. I need to continue to see everything because you're able to react faster. I feel like that's my game, react with speed."

Allen, meanwhile, has started all three preseason games and played well. He has continued to progress after struggling in the first few games last season.

"We've seen Nate grow because his mind has slowed down," Davis said. "And he's seeing more. He understands his landmarks, where his eyes need to be placed ... All those things are growing and you're seeing Nate play better and better."